Newsletter of the Big Bend Astronomical Society, Inc. October, 1999 Jim Walker, Editor

        The meeting was called to order a little after 7:30 PM by Vice President Bernie Zelazny, in the absence of President Bill Baker. There were 11 people present. Secretary Jim Walker moved the acceptance of the minutes of the previous meetings as printed in the August-September Newsletter. The minutes were so approved, and there were no corrections or additions.
        In view of his role as Chair of the Nominating Committee and also a candidate for office, Vice President Bernie Zelazny asked Secretary Jim Walker to preside over the remainder of the business meeting. Other members of the Nominating Committee are Judy Brueske-Plimmer and Andy Anderson.
        Noting that our bylaws prohibit a member of the Nominating Committee also serving as a candidate for office, Jim Walker entertained a motion waiving a suspension of the rules in this regard, ruling that a suspension would require a 2/3 majority under Roberts Rules of Order. Doug McCombs moved the suspension of the rules in this regard and Barbara Walker seconded. The motion carried 9 for, none against, without discussion.
        Bernie Zelazny then presented the following slate of candidates for the year 2000: President, Bernie Zelazny; Vice President, John Bell; Secretary, Jim Walker; Treasurer, Betty Grimm; and Board Members at Large, Terence Eakens and W. Parks Goodwin. Doug McCombs moved the acceptance of the proposed slate and Willeen Austin seconded. The motion carried unanimously. Nominations from the floor were opened, and there were none. Ballots will be mailed to members as soon as practicable.
        The business meeting was adjourned about 8:00 PM. Doug McCombs then presented our program.

        The grit is placed between the tool and the mirror, and the person grinding the mirror changes the direction of each push by a small amount, walking around the mirror in a constant direction (or alternatively, rotating the mirror by a small amount). As the grinding progresses, the mirror becomes concave, dish-like, and the tool becomes convex. Fining uses #180 and #120 grits; smoothing uses white aluminum oxide, 25 to 9 micrometers; and polishing uses cerium oxide or red rouge.
        When the mirror is ground and polished to a spherical curvature (see Figure B), it is then necessary to convert the sphere to a paraboloid, a process called figuring. [Some telescopes use spherical mirrors, but
many use parabolic mirrors.] The process of figuring deepens the curvature of the mirror by removing a small amount of glass mostly in the middle of the mirror. The tool is covered with melted Burgundy or Swedish pine pitch and pressed down into the mirror. To keep the pitch from sticking to the mirror, the mirror is coated
with a slurry of the polishing compound. A number of grooves are cut into the pitch covering the tool at intervals of about 1 inch, forming a rectangular pattern. The tool, covered in pitch, is then loaded with cerium oxide and moved back and forth across the mirror as shown in Figure D. The direction of movement of the tool across the mirror changes slightly after each series of passes shown by the jagged lines in Figure D.
        Doug explained that machines can do much of the work of grinding and polishing, and that it is more economical for a technician to monitor five or six machines than to do all the work by hand. A mirror must be tested to insure a spherical curvature before figuring, and a paraboloid curvature after. Doug indicated that testing is itself a major area, maybe even a whole ‘nother presentation. Some of us will have a better appreciation of the amount of sophisticated labor involved the next time we see a crisp image through a telescope.

        Los Angeles. Ushering in a new era in rocketry, a multinational company has launched a communications satellite into space from a platform floating in the Pacific  cean, the first such launching from sea rather than from land. The 200-foot-tall rocket recently lifted off from the launching pad, a converted offshore oil drilling platform.
        The achievement is significant because using an offshore platform allows launchings to be conducted at the equator, where the rotation of the earth's surface is the fastest. The rotation gives the rocket a boost, allowing it to use less fuel or carry a heavier payload than a similar rocket launched from another latitude.

        Jupiter was at opposition on October 23. In this configuration, a planet rises and sets nearly with the sun. A mere 368 million miles away, Jupiter is at its closest approach between October, 1987, and September, 2010. You may have noticed how bright it has been in the evening, and especially during the early morning
hours, -2.9 magnitude. This is a great time to view one of the glories of the solar system.
        At opposition, the apparent size of a planet is at or near its largest. As a result, the cloud bands an Jupiter have been especially well defined lately.
        Saturn is also nearing opposition, and is now prominent in the morning to the east of Jupiter. Mars is prominent in the southwest after sunset. Venus has been very bright in the east in the early morning, - 4.6 mag. Remember, negative magnitudes mean greater brightness.

        On Monday, November 15, Mercury will move across the sun from about 3:10 PM to 4:10 PM CST. The planet will appear as a small spot about 10 arcminutes in diameter moving across the northeastern portion of the sun very near the edge. The silhouette of Mercury will look like a small round and very dark sunspot about 1/200 the diameter of the sun.
        Anyone who wishes is invited to view this transit safely by eyepiece projection with Jim and Barbara Walker.
        DO NOT UNDER ANY CONDITIONS try to view this event directly through binoculars or a telescope without a HIGH QUALITY SOLAR FILTER. If you have any question about viewing this transit of Mercury, or anything else involving the sun, please consult with an experienced person.

        If you receive a paper copy of this Newsletter, please use the enclosed ballot to vote for officers and board members for the year 2000.
        If you receive the Newsletter by email, you will receive your ballots by US Mail. Ballots may be returned by mail, or may be taken to the November meeting, where they will be counted.